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March 29th, 2011, 04:46 PM   #1
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Probability, help me, please, So confusing

The problem is
Find the probability when have at least 2 heads in 3 tosses of a coin
I can solve it by the list. But is's too slow if I have a big number

Like, The probability when have at least 3 heads in 5 tosses
Somebody solve it, by use combination like 5C3/(1/2)^5

But I'm so confused, the we use conbination if the position of heads and tails are not important. But here, the position is important.

Why everybody solve it by using the combination
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March 29th, 2011, 04:53 PM   #2
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Re: Probability, help me, please, So confusing

See this topic for my "explanation" of the use of combinations for this type of problem:

http://www.mymathforum.com/viewtopic.php?f=24&t=19861
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